U.S. OFFICIALS have pleaded with migrants to stay home for now, playing for time as they scramble to devise a humane, orderly asylum system to replace the Trump administration’s draconian one. Those pleas have fallen on deaf ears. The resulting surge of illegal border crossings has become a crucible for the new administration just weeks after President Biden assumed office.

No doubt, the toxic medley of push factors driving migrants northward from Central America is potent: violence, poverty, corruption, climate change and, in recent months, natural disasters. But the president’s own policies are unintentionally intensifying the spike in families and unaccompanied minors crossing the border, which began even before he took office. By rightly refusing to summarily expel children who cross the border illegally — or separate them from their families, as the Trump administration did — Mr. Biden seems to have nullified official calls for migrants to bide their time.

As the numbers of undocumented families, lone teenagers and even younger children apprehended at the border climb, Homeland Security officials are shifting gears by preparing to transform detention centers into short-term waystations from which families will be swiftly screened, tested for the coronavirus and then allowed to join relatives already in the United States. The goal, officials say, is to release parents and children within 72 hours of their arrival in the country, processing roughly 100 migrants per day. They would then face waits of up to several years for their asylum cases to be adjudicated.

That is a humane and decent approach that would minimize the harm inflicted on minors, for whom detention is often traumatic. President Donald Trump regarded trauma, in the form of breaking up families, as a fine tool of dissuasion when it came to illegal immigration. Mr. Biden, to his credit, is charting a different path.

That path comes with potential costs both to his political and legislative prospects. The White House was never likely to convince many Republicans, still in thrall to Mr. Trump, of the merits of a more humane asylum policy, let alone broader goals of legalizing 11 million long-term unauthorized immigrants, or even “dreamers” brought to the country as children. But a chaotic flood of migrants crossing the border, and the resulting GOP demagoguery about “catch-and-release,” increases the risk that moderates and independents could recoil from Mr. Biden’s push for immigration reform.

The only real solution is a long-term one. It involves sending aid to Central America that improves conditions in the region; beefing up immigration courts with a major infusion of new judges to expand their capacity so that asylum claims are processed quickly and the years-long case backlog is shrunk; and, perhaps, screening and processing asylum applicants in Central America, perhaps Guatemala — a prospect that seems far off at best.

For the time being, Mr. Biden must manage a balancing act, reestablishing the United States’ traditional role as a beacon for beleaguered immigrants while also avoiding a massive new wave of illegal immigration that many Americans would object to.

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